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Old 04-02-2003, 07:48 AM
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novajohnb novajohnb is offline
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I personally run 11.5:1 compression on 94 premium in a "small" block 412 chevy. This is with a holley carb- no fuel injection. It has a big cam (264/ 270 duration at 0.050"), aluminum heads, big universal fit griffin Al radiator, stewart water pump, coolant hoses from pump to center of heads, etc..

The big cam bleeds off cylinder pressure, and the cooling system has to be up to snuff.

I checked the bottom end over the winter, no hint of detonation.

I have gone as fast as 10.91 @ 122 MPH with this combo in a 3500 lb street car on 94 pump gas alone. When the weather gets cooler and denser, I chicken out and mix in some race gas for "peace of mind."

It has about 210 lbs of cranking pressure. I _have_ run into detonation at 200 lbs of cranking pressure in a totally different (much milder) combo with iron heads.

Static compression ratio and camshaft profile (intake closing, etc...) go hand in hand to determine the dynamic compression ratio.

Do a web search for "dynamic compression ratio calculator." I think you can push the limits of the calculator. In other words it is a little conservative if anything.
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